After reading all the threads on here and other forums about Super vs Standard and specifically the EP3 I asked Honda UK and also Hendy Honda, the main dealer in Exeter who service my car.
A technical adviser from customer services at Honda UK told me that the EP3 is optimised for 97+RON unleaded fuel and that anything less will lead to some retardation to avoid knocking. He also said that performance
would be marginally reduced but that the car will quite happily run on 95RON standard unleaded fuel without any ill effects, however he also said that use of 97+RON fuel may increase the life of the engine due to it running optimally and should show a marginal improvement to fuel efficiency. The unofficial view of the adviser was that certain premium fuel brands (namely BP and Shell) were likely to have a more beneficial effect (particularly on engine life and fuel efficiency) than other brands due to their additional cleansing elements and production quality and that the other end of that spectrum was supermarket fuels that admittedly offer good value for money in the short-term but may not look after your engine as well. His view was "I never used supermarket fuel in my S2000".
AtHendy Honda's service department an ex-Honda technician turned service adviser told me that the EP3 uses 95RON unleaded fuel and has no requirement for or beneficial effect from using super unleaded.
So, same old story, possibly minor benefits in efficiency and engine life but probably not any perceivable performance increase from 97+RON fuel unless you have upgraded your engine and ECU in such a way as to benefit from the higher octane. For me the difference in cost between standard and super unleaded is not big enough to worry about and if using Shell/BP advanced fuel leads to my engine being even slightly healthier for longer i'll take the hit. Use a fuel comparison website like petrolprices.com (or their phone app) and you'll soon find cheaper fuel than your average garage and you can often find 5p per litre discount offers anyway if you look around online and in the papers.
The anomaly in this subject appears to be Tesco Momentum 99RON, higher octane than most super unleaded and allegedly still packed full of beneficial additives, at least according to them. Cheaper than Shell/BP often too. No good for me when the nearest garage offering it is 15 miles away though! A few worrying comments online about negative impacts of this fuel, possibly linked to the high Ethanol content but who knows what is and is not bulls**t? Their much lauded (by them) performance testing by Thorney Motorsport on VXR Vauxhall's has come into question since Thorney came out with a statement that they would not and could not recommend the fuel after unresolved engine problems that they attributed to the fuel itself.
The only way we'll ever get real answer to these questions about performance would be if somebody we trust (like TDI) did a comparison dyno test on specific models with Shell/BP/Tesco/generic super unleaded to see which is best on a standard and tweaked Type-R, somebody we trust to tell us the truth. The problem being that the fuels will constantly change and the data so it would only be the basic data that would stand up. The only known known is that if your engine has been highly tuned and/or turbocharged then you should see a decent performance benefit from using good quality high octane fuels, as long as your engine and performance parts are well developed.
For me Shell super unleaded is the fuel I will stick in my EP3 for now then! Because their entire business is built on an image of developing and providing high quality fuel they cannot risk it being found that their fuel is s**t so have no choice but to make provide quality fuels, unlike supermarkets and fuel producers whose product image is not premium. I'd rather invest a little more money in my car on that premise. I also get to waste money on buying more Lego Ferrari toys for my kids this Christmas!